Viscous liquids, such as wax or sugar syrup, turn to a solid at room temperature, making atomization and spraying of such liquids difficult. Heating of supply pipes, valves, nozzles and other components of the spray device necessary for effective spraying of such liquids has been an ongoing problem in the industry. Moreover, for energy conservation purposes, many companies desire to use surplus heat from the manufacturing process in heating the spray gun components and supply lines.
Automatically operated spray guns commonly have a multiplicity of pressurized liquid and air lines connected to the spray gun body, typically through pipe nipples arranged about mixing and nozzle sections of the spray gun body. Encasing the gun body in a metal heating jacket through which a heating fluid can be circulated has resulted in complicated, difficult to manufacture, devices. In lieu thereof, it has been the practice to wrap metal heating tubing around the spray gun, snaking it in and around the liquid and air connections to form a heated surrounding enclosure. This practice is time consuming, results in a one of a kind heating jacket construction, is unpredictable in performance, and cumbersome to service in the field without time consuming, disassembly and reassembly. Hence a need has existed for a relatively simple spray gun heating jacket which can be operated with predictability and which permits easy removal of the heating jacket and/or spray gun for service and/or field replacement.